1. Field of the Invention
The invention is related to a method and a device for opening and transporting on printed products with respectively at least two sheets held together over a fixed edge, comprising a conveying device with transport grippers arranged behind one another at a distance from one another and driven in a conveying direction (F), which are designed to hold the printed products at their fixed edge, as well as comprising opening devices arranged underneath the conveying device, which are meant to open the printed products, wherein the opening device comprises gas supply means for producing a gas flow, by means of which the sheets of the printed product are capable of being fanned open in a free edge zone, and an opening element introducible into the fanned open free edge zone.
2. Description of Related Art
Printed products with several sheets, which are held together over a fixed edge, for the execution of certain processing steps have to be opened. Thus, for example, the printed products for inserting objects between two product parts of a folded or bound printed product have to be opened. In another application, printed products have to be opened, in order for these to be able to be placed on a saddle, so that the opened and placed on saddle printed products are capable of being brought to a collecting device. Furthermore, the opening of a printed product is also necessary, when an object is to be stuck on to a side of a sheet located inside, or when a side of a sheet located inside has to be printed on.
From EP 0 647 582 A1 it is known that printed products to be opened are held at their fixed edge and transported essentially in vertically suspended position, wherein the front edge zone opposite the fixed edge is supported by a supporting element. A suction head as an opening element is inserted between the printed products from above the supporting element and from above grips in between the printed products and lies against these, while a further suction head lies against the printed product from below. As a result, the product parts are held on both sides during the complete opening process. The device is designed to open folded individual sheets, or to open doubly folded products, which are folded a first time and then a second time at right angles to the first fold. The doubly folded product must not be cut, in order for it to be able to be reliably opened. The opened printed product subsequently with its opened edge zone is transferred to a helical holding open device.
EP 1 908 714 B1, in contrast, describes an opening device with a wedge element, by means of which the opening of a folded document is possible while it is being conveyed.
EP 1 090 867 B1 describes a device for opening folded printed products with a pre-fold, wherein the printed products for this purpose are inserted into bags and with mechanical means, such as clamping stops, hooking elements as well as a pressure rail with gripper hooks are opened. This device, however, only works for two-page printed products with a positive overlap.
EP-B-0 577 964, in turn, describes a device and a method for opening multi-page printed products. The printed products at a free edge are subjected to a gas flow, which leads to a fanning open of the sheets in this edge zone. Subsequently an opening element is inserted into the fanned open edge zone, which opens the product for the further processing. For a controlled fanning open of the printed product the printed product in accordance with a specific embodiment is inserted into a receiving cell with side walls. In doing so, the side walls serve to limit the fanning open, which as a result becomes more uniform.
For reasons of processing efficiency, for example, printed products conveyed one behind the other shall be opened during the uninterrupted conveyance. For this reason, it is disadvantageous in a continuous conveying process, if the printed products for being opened have to be brought to individual receiving cells. An opening method of this kind therefore during the conveyance of the printed products only works, when the conveying direction of the printed products runs in parallel to the main plane of the sheets, as this is also indicated in EP-B-0 577 964.